Such metal fibers when straight are employed for example as concrete additives for improving the performance of concrete with respect to tensile, pressure, and shock loadability, which can for instance prevent a crack that forms in the concrete from progressing due to increased expansion. Metal fibers with bent ends, that is U-shaped like fasteners, are used as a connecting element in soft and elastic materials, for example in the broadest context in the wood industry, in the construction and furniture industries, and in the plastics industry.
As a rule, in all of these applications it is desirable to influence the metal fibers with respect to their shape such that they are able to absorb tensile forces from the materials surrounding them. To this end, in metal fibers for use in concrete and usually formed as steel wire fibers, it is common practice to add for instance bends at the fiber ends, where the tensile forces that can be absorbed because of this are relatively limited because the hook shape of the steel wire fiber changes under tensile stress, that is, can be pulled out of the channel it created. In principle only the friction fit between fiber and concrete is improved by the hook shape at the two wire steel fiber ends.
Such a shape is hardly possible in staples that are used for instance in electrical tackers and a plurality of which to this end are glued together in stacks, so that in this case it is always necessary to work with fasteners that have relatively long legs in order to apply sufficient frictional forces by the material surrounding the fasteners to prevent the fasteners from being easily pulled out.